Contributors

Usage

Using the TPL5111 isn't too hard but there's a few things to watch out for. First up, do not give it 9V power, use 3-5V only!

Use the TPL5111 with any board that has an Enable pin. If an Enable pin isn't available, the Reset pin can sometimes be used - but often won't give you as much power savings!

Here's an example with an ESP8266 Feather. Power the Feather by USB or battery as normal

Make sure to provide the power to the VDD and GND pins.

Remember The VDD pin has to be always powered so you cannot connect it to the power pin you are enabling/disabling!

Then connect your project's Enable pin to the ENout pin, and also connect up the GND pin. Use a DONE pin from your microcontroller to signal when the TPL can disable power: when the DONE pin goes from low to high, that will turn off the TPL's power transistor.

Turn the trim potentiometer clockwise to make the resistance lower - measure the resistance between Delay and GND and check against the table below to make sure you get the timing you want

In this project I'm using the ESP8266 Feather's digital #5 as the DONE signal pin. It is lightly pulled down so just set to an Output and High when you're done!

For the code, we toggle the DONE pin high and low forever to make sure it gets 'caught' by the TPL (it may not be necessary but it doesn't hurt!)

If the TPL doesn't get a DONE signal, it will reset the board with a short ENABLE toggle when the timeout is reached (e.g. before the next cycle)

Notes on the Delay Pin

The delay pin is a little more complicated than you may first think!

First, do not connect a voltage here, instead it uses a resistor to determine the delay timing.

Second, it does not continuously sample the resistor, it only does it once when power is applied. So set the delay you want, then power up the breakout.

Third, you can instantly turn on the project by connecting Delay to ground. By default we have a pushbutton on board, you can connect your own button if you like

Fourth, the resistance is not linear with the time delay, rather there is a complex algorithm to set the time based on resistance. You can check the datasheet for the precise calculation, or use this rough table:

1 Seconds

5.2 KΩ

2 Seconds

6.79 kΩ

3 Seconds

7.64 kΩ

4 Seconds

8.3 kΩ

5 Seconds

8.85 kΩ

6 Seconds

9.26 kΩ

7 Seconds

9.71 kΩ

8 Seconds

10.18 kΩ

9 Seconds

10.68 kΩ

10 Seconds

11.2 kΩ

20 Seconds

14.41 kΩ

30 Seconds

16.78 kΩ

40 Seconds

18.75 kΩ

50 Seconds

20.047 kΩ

1 Minute

22.02 kΩ

2 Minutes

29.35 kΩ

3 Minutes

34.73 kΩ

4 Minutes

39.11 kΩ

5 Minutes

42.90 kΩ

6 Minutes

46.29 kΩ

7 Minutes

49.38 kΩ

8 Minutes

52.24 kΩ

9 Minutes

54.92 kΩ

10 Minutes

57.44 kΩ

20 Minutes

77.57 kΩ

30 Minutes

92.43 kΩ

40 Minutes

104.67 kΩ

50 Minutes

115.33 kΩ

1 Hour

124.91 kΩ

1 Hour 30 Minutes

149.39 kΩ

2 Hours

170 kΩ

Given that we put a 200 kΩ trimpot on the board, you may find it difficult to get precise timing if you need short delays. In that case, you can use any resistor you want. First, cut the trace on the back of the PCB

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